Process of concentrating nitric acid.



N. TITLESTAD. PRocEss or coNcENTR-Mms mmc Aem.

APPLICATION FILED SEPT. 8, 19H.

Patented Apr. 11, 1916.

JWM/75p UNITED STAE'IElv PATENT OFFICE.

NIKLAI TITLESTAD, 0F RJUKAN, NORWAY, ASSIGNOR T0 NORSK HYDRO-ELEKTRISK KVAELSTOFAKTIESELSKAB, OF CHRISTIANIA, NORWAY.

PROCESS 0F CONCENTRATING NITE-IC ACID.

specification of Letters Patent.

Patented Apr. 11, 1916.

T 0 all whom it may concern Be it known that I, NIKOLAI TITLESTAD, a subject of the King of Norway, residing at Rjukan, Norway, have invented certain new and useful Improvements in Processes of ConcentratingNitric Acid; and I do hereby declare the following to be. a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has for its object a process of concentrating nitric acid.

In the processes hitherto employed for concentrating nitric acid in counter current with sulfuric acid or other similarconcentrating agents one has proceeded in the manner, that nitric acid has been introduced into the concentration apparatus either as a liquid or as a vapor. In the first instance viz. when the nitric acid is introduced as a liquid the apparatus must be directly or indirectly heated to effect the distillation of the concentrated acid. In the latter case that is when introducing the acid as a vapor theapparatus as is known must be cooled either by the arrangement of cooling dcvices or hy introducing a cooling fluid such as for instance described in the Norwegian patent specification No. 23152-5.

According to the present invention a very rational concentration is obtained by combinin'g'the known methods in the manner that the acid to be concentrated is introduced into a concentration apparatus as a mixture of vapor and liquid. This mixture of liquid and vapor is suitably produced b y boilingr nitric acid outside of thc coiurentration apparatus. Uy proceedingr in this mun-- ner important advantages are obtained. As such is to be mentioned that the concentration process could be carried out without further heating because the amount of heat supplied by the mixture together with the,l

reaction heat developed during the concentration process is suilicient to ciiect the distillation of the concentrated nitric acid. Further the evaporation of the nitric acid which is still in a liquid state etl'ects a reduction and distribution ot' the temperature in such manner, that the temperature at no point in the apparatus becomes too high, that is so high as to have an injurious influence upon the concentration process. A very important advantage consists` in that the control of the working ol' the apparatus from one point is made possible, it being only necessaryto regulate the supply of the mixture of vapor and liquid in order to obtain a uniform working oi the concentration process.

It is obvious, that by proceeding in the manner above described important advantages are obtained and that the technical ei'ect is considerably improved in comparison to the processes hitherto employed. Thus it is made possible by this process to concentrate nitric acid in an apparatus of a very simple construction having no heating arrangementsI for the distillation of the coiu'entrated nitric acid or cooling means for controlling the temperature s a result ot' these simplifications ot' the plant the regulation of the apparatus is greatly facilitatcd, which also increases the safety of operation. rl'he production is thereby improved in quantity as well as in quality. rl`lic coiuentrating power of the sulfuric acid is utilized to the highest extent and the loss ot' `sulfuric acid is reduced to a minimum.

In the accompanying drawing is illustrated an apparatus lor carrying out my invention. partly in elevation and partly in vertical section.

ln this drawing` l is the concentrating chamber, 2 a vessel containing concentrated sulfuric. acid or other equivalent concentrating agent. The coimntrating agent is supplied from vcssel-2 to the top of the tower or concentrating chamber l through a pipe il. The nitric acid to be concentrated flows from a reservoir l through pipe 5 into the bottom ot the tower l. The pipe 5 is .surrounded b v a steam heating chamber ti. liv suitably adjustingr the supply of steam to chamber in relation to the Supply of dilute nitric acid passimcr through pipe 5, the nitric acid iu this pipe is transformed into the desired mixture of vapor and liquid. The nitricacid vapors escaping from the top of the tower are passed through a condenser T. from which concentrated acid is withdrawn at S. The concentrating agent escapes at E) from the bottom of the tower.

Claims:

l. The process of concentrating nitric acid in counter current with a suitable concentrating agent` which comprises Supplyintrr said nitric acid to said concentrating agent as a mixture of liquid and vapor.

In the process of concentrating nitric In testimony that I claixnrthe foregoing acid 1n counter current with sulfurlc acid as my 1nvent10n, Ivhave signed my name 1n the step which conslstsin introduclng the presence of two siibscrlbing wltnesses.

nitric acid into the concentration apparatus NIKOLAI TITLESTAD. as u I nixtureof liquid and vapor, produced \Vitnesses: by=builing the nitric acid to be concentrated M. E. GUTTORUSEN.

outside of the concentration apparatus. C. F. HANSEN. 

